Abstract: This study aimed to investigate the effects of different oligosaccharides on the quality and volatile aroma compounds of fermented green tea. Sucrose, isomalto-oligosaccharides, galacto-oligosaccharides, and fructo-oligosaccharides were added to Mao Jian green tea extract and subjected to fermentation with Lactiplantibacillus plantarum at 37 ℃. Changes in physicochemical properties, monomeric phenolic compounds, antioxidant activity, organic acid composition, and volatile compounds were analyzed before and after 48 h of fermentation. The results showed that, compared with sucrose-supplemented fermented green tea, oligosaccharide supplementation significantly increased total phenolic and flavonoid contents, monomeric phenol content changed significantly (P<0.05). Among them, galacto-oligosaccharide supplementation yielded the highest total phenolic content (2552.21 mg GAE/L), while isomalto-oligosaccharide supplementation yielded the highest total flavonoid content (365.83 mg RE/L). Oligosaccharide supplementation also markedly enhanced antioxidant activity (P<0.05). Galacto-oligosaccharide supplementation produced the strongest DPPH radical scavenging activity (79.20%) and ferric-reducing antioxidant power (22.56 mmol Trolox/L); however, fructo-oligosaccharide supplementation produced the highest ABTS radical scavenging activity (89.00%). In addition, significant differences (P<0.05) in organic acid were observed between oligosaccharide-supplemented samples and sucrose-supplemented samples. Oligosaccharide-supplemented samples had higher total volatile aroma compound levels than sucrose-supplemented samples, with increased alcohol, alkene, and ketone levels, and the formation of new volatile aroma compounds, such as 2-methyl-1-butanol, lauric acid, and ethyl acetate, thereby conferring distinctive aroma characteristics. Among the oligosaccharides, isomalto-oligosaccharide supplementation yielded the highest volatile aroma compound content (43987.09 μg/L). Overall, these findings indicate that oligosaccharide supplementation not only significantly enhances the nutritional composition and antioxidant activity of fermented green tea but also enriches its aroma profile, providing a theoretical basis for the development of functional fermented tea products.